ACI-ASTM CH20 (SCS17, J93402) Cast Stainless Steel
ACI-ASTM CH20 steel is an austenitic stainless steel formulated for casting. Cited properties are appropriate for the heat treated (HT) condition. CH20 is the designation in both the ACI and ASTM systems for this material. J93402 is the UNS number.
It has a fairly high tensile strength and a moderately high ductility among cast austenitic stainless steels.
The graph bars on the material properties cards below compare ACI-ASTM CH20 steel to: cast austenitic stainless steels (top), all iron alloys (middle), and the entire database (bottom). A full bar means this is the highest value in the relevant set. A half-full bar means it's 50% of the highest, and so on.
Mechanical Properties
Brinell Hardness
190
Elastic (Young's, Tensile) Modulus
200 GPa 29 x 106 psi
Elongation at Break
38 %
Fatigue Strength
290 MPa 42 x 103 psi
Poisson's Ratio
0.27
Shear Modulus
78 GPa 11 x 106 psi
Tensile Strength: Ultimate (UTS)
610 MPa 88 x 103 psi
Tensile Strength: Yield (Proof)
350 MPa 50 x 103 psi
Thermal Properties
Latent Heat of Fusion
310 J/g
Maximum Temperature: Corrosion
440 °C 820 °F
Maximum Temperature: Mechanical
1100 °C 2010 °F
Melting Completion (Liquidus)
1410 °C 2570 °F
Melting Onset (Solidus)
1430 °C 2610 °F
Specific Heat Capacity
480 J/kg-K 0.12 BTU/lb-°F
Thermal Conductivity
14 W/m-K 8.1 BTU/h-ft-°F
Thermal Expansion
15 µm/m-K
Electrical Properties
Electrical Conductivity: Equal Volume
2.0 % IACS
Electrical Conductivity: Equal Weight (Specific)
2.3 % IACS
Otherwise Unclassified Properties
Base Metal Price
20 % relative
Density
7.8 g/cm3 490 lb/ft3
Embodied Carbon
3.7 kg CO2/kg material
Embodied Energy
53 MJ/kg 23 x 103 BTU/lb
Embodied Water
180 L/kg 21 gal/lb
Common Calculations
PREN (Pitting Resistance)
25
Resilience: Ultimate (Unit Rupture Work)
200 MJ/m3
Resilience: Unit (Modulus of Resilience)
300 kJ/m3
Stiffness to Weight: Axial
14 points
Stiffness to Weight: Bending
25 points
Strength to Weight: Axial
22 points
Strength to Weight: Bending
21 points
Thermal Diffusivity
3.7 mm2/s
Thermal Shock Resistance
15 points
Alloy Composition
Among cast stainless steels, the composition of ACI-ASTM CH20 steel is notable for containing comparatively high amounts of chromium (Cr) and nickel (Ni). Chromium is the defining alloying element of stainless steel. Higher chromium content imparts additional corrosion resistance. Nickel is primarily used to achieve a specific microstructure. In addition, it has a beneficial effect on mechanical properties and certain types of corrosion.
| Fe | 54.7 to 66 | |
| Cr | 22 to 26 | |
| Ni | 12 to 15 | |
| Si | 0 to 2.0 | |
| Mn | 0 to 1.5 | |
| Mo | 0 to 0.5 | |
| C | 0 to 0.2 | |
| P | 0 to 0.040 | |
| S | 0 to 0.040 |
All values are % weight. Ranges represent what is permitted under applicable standards.
Followup Questions
Similar Alloys
Further Reading
ASTM A743: Standard Specification for Castings, Iron-Chromium, Iron-Chromium-Nickel, Corrosion Resistant, for General Application
Machining of Stainless Steels and Super Alloys: Traditional and Nontraditional Techniques, Helmi A. Youssef, 2016
Welding Metallurgy and Weldability of Stainless Steels, John C. Lippold and Damian J. Kotecki, 2005
Corrosion of Austenitic Stainless Steels: Mechanism, Mitigation and Monitoring, H. S. Khatak and B. Raj (editors), 2002
Austenitic Stainless Steels: Microstructure and Mechanical Properties, P. Marshall, 1984
ASM Specialty Handbook: Stainless Steels, J. R. Davis (editor), 1994
Advances in Stainless Steels, Baldev Raj et al. (editors), 2010